1 SESSION LAYER PROTOCOL FOR CITADEL/UX
2 (c) 1995-2002 by Art Cancro et. al. All Rights Reserved
8 This is an attempt to document the session layer protocol used by the
9 Citadel/UX system, beginning with version 4.00, which is the first version
10 to implement a client/server paradigm. It is intended as a resource for
11 programmers who intend to develop their own Citadel clients, but it may have
15 IMPORTANT NOTE TO DEVELOPERS!
16 -----------------------------
18 Anyone who wants to add commands or other functionality to this protocol,
19 *please* get in touch so that these efforts can be coordinated. New
20 commands added by other developers can be added to this document, so we
21 don't end up with new server commands from multiple developers which have
22 the same name but perform different functions. If you don't coordinate new
23 developments ahead of time, please at least send in an e-mail documenting
24 what you did, so that your new commands can be added to this document.
26 The coordinator of the Citadel/UX project is Art Cancro
27 <ajc@uncensored.citadel.org>.
30 CONNECTING TO A SERVER
31 ----------------------
33 The protocols used below the session layer are beyond the scope of this
34 document, but we will briefly cover the methodology employed by Citadel/UX.
36 Citadel/UX offers Citadel BBS service using TCP/IP. It does so via a
37 multithreaded server listening on a TCP port. Older (4.xx) versions employed
38 an inetd-based server.
40 The port number officially assigned to Citadel by the IANA is 504/tcp. Since
41 our session layer assumes a clean, reliable, sequenced connection, the use
42 of UDP would render the server unstable and unusable, so we stick with TCP.
45 GENERAL INFORMATION ABOUT THE SERVER
46 ------------------------------------
48 The server is connection-oriented and stateful: each client requires its own
49 connection to a server process, and when a command is sent, the client must
50 read the response, and then transfer data or change modes if necessary.
52 The session layer is very much like other Internet protocols such as SMTP
53 or NNTP. A client program sends one-line commands to the server, and the
54 server responds with a three-digit numeric result code followed by a message
55 describing what happened. This cycle continues until the end of the
58 Unlike protocols such as FTP, all data transfers occur in-band. This means
59 that the same connection that is used for exchange of client/server
60 messages, will also be used to transfer data back and forth. (FTP opens a
61 separate connection for data transfers.) This keeps protocol administration
62 straightforward, as it can traverse firewalls without any special protocol
63 support on the firewall except for opening the port number.
69 The server will respond to all commands with a 3-digit result code, which
70 will be the first three characters on the line. The rest of the line may
71 contain a human-readable string explaining what happened. (Some client
72 software will display some of these strings to the user.)
74 The first digit is the most important. The following codes are defined for
75 this position: ERROR, OK, MORE_DATA, LISTING_FOLLOWS, and SEND_LISTING.
77 The second and third digits may provide a reason as to why a command
78 succeeded or failed. See ipcdef.h for the available codes.
80 ERROR means the command did not complete.
81 OK means the command executed successfully.
82 MORE_DATA means the command executed partially. Usually this means that
83 another command needs to be executed to complete the operation. For example,
84 sending the USER command to log in a user usually results in a MORE_DATA
85 result code, because the client needs to execute a PASS command to send the
86 password and complete the login.
87 LISTING_FOLLOWS means that after the server response, the server will
88 output a listing of some sort. The client *must* read the listing, whether
89 it wants to or not. The end of the listing is signified by the string
90 "000" on a line by itself.
91 SEND_LISTING is the opposite of LISTING_FOLLOWS. It means that the client
92 should begin sending a listing of some sort. The client *must* send something,
93 even if it is an empty listing. Again, the listing ends with "000" on a line
95 BINARY_FOLLOWS and SEND_BINARY mean that the client must immediately send
96 or receive a block of binary data. The first parameter will always be the
98 ASYNC_MESSAGE_FOLLOWS means that an asynchronous, or unsolicited, message
99 follows. The next line will be one of the above codes, and if a data transfer
100 is involved it must be handled immediately. Note that the client will not
101 receive this type of response unless it indicates to the server that it is
102 capable of handling them; see the writeup of the ASYN command later in this
108 Zero or more parameters may be passed to a command. When more than one
109 parameter is passed to a command, they should be separated by the "|"
112 In this example, we're using the "SETU" command and passing three
113 parameters: 80, 24, and 260.
115 When the server spits out data that has parameters, if more than one
116 parameter is returned, they will be separated by the "|" symbol like
119 In this example, we just executed the "GETU" command, and it returned us
120 an OK result code (the '2' in the 200) and three parameters: 80, 24, and
127 This is a listing of all the commands that a Citadel/UX server can execute.
132 This command does nothing. It takes no arguments and always returns
133 OK. It is intended primarily for testing and development, but it might also
134 be used as a "keep alive" command to prevent the server from timing out, if
135 it's running over a transport that needs this type of thing.
138 ECHO (ECHO something)
140 This command also does nothing. It simply returns OK followed by whatever
146 Terminate the server connection. This command takes no arguments. It
147 returns OK and closes the connection immediately.
152 Log out the user without closing the server connection. It always returns
153 OK even if no user is logged in.
156 USER (send USER name)
158 The first step in logging in a user. This command takes one argument: the
159 name of the user to be logged in. If the user exists, a MORE_DATA return
160 code will be sent, which means the client should execute PASS as the next
161 command. If the user does not exist, ERROR is returned.
166 The second step in logging in a user. This command takes one argument: the
167 password for the user we are attempting to log in. If the password doesn't
168 match the correct password for the user we specified for the USER command,
169 or if a USER command has not been executed yet, ERROR is returned. If the
170 password is correct, OK is returned and the user is now logged in... and
171 most of the other server commands can now be executed. Along with OK, the
172 following parameters are returned:
174 0 - The user's name (in case the client wants the right upper/lower casing)
175 1 - The user's current access level
178 4 - Various flags (see citadel.h)
180 6 - Time of last call (UNIX timestamp)
183 NEWU (create NEW User account)
185 This command creates a new user account AND LOGS IT IN. The argument to
186 this command will be the name of the account. No case conversion is done
187 on the name. Note that the new account is installed with a default
188 configuration, and no password, so the client should immediately prompt the
189 user for a password and install it with the SETP command as soon as this
190 command completes. This command returns OK if the account was created and
191 logged in, or ERROR if another user already exists with this name. If OK,
192 it will also return the same parameters that PASS returns.
194 Please note that the NEWU command should only be used for self-service user account
195 creation. For administratively creating user accounts, please use the CREU command.
198 SETP (SET new Password)
200 This command sets a new password for the currently logged in user. The
201 argument to this command will be the new password. The command always
202 returns OK, unless the client is not logged in, in which case it will return
206 CREU (CREate new User account)
208 This command creates a new user account AND DOES NOT LOG IT IN. The argument to
209 this command will be the name of the account. No case conversion is done
210 on the name. Note that the new account is installed with a default
211 configuration, and no password. This command returns OK if the account was created,
212 or ERROR if another user already exists with this name.
214 Please note that CREU is intended to be used for activities in which a system
215 administrator is creating user accounts. For self-service user account creation,
216 use the NEWU command.
220 LKRN (List Known Rooms with New messages)
222 List known rooms with new messages. If the client is not logged in, ERROR
223 is returned. Otherwise, LISTING_FOLLOWS is returned, followed by the room
224 listing. Each line in the listing contains the full name of a room, followed
225 by the '|' symbol, and then a number that may contain the following bits:
228 #define QR_PERMANENT 1 /* Room does not purge */
229 #define QR_PRIVATE 4 /* Set for any type of private room */
230 #define QR_PASSWORDED 8 /* Set if there's a password too */
231 #define QR_GUESSNAME 16 /* Set if it's a guessname room */
232 #define QR_DIRECTORY 32 /* Directory room */
233 #define QR_UPLOAD 64 /* Allowed to upload */
234 #define QR_DOWNLOAD 128 /* Allowed to download */
235 #define QR_VISDIR 256 /* Visible directory */
236 #define QR_ANONONLY 512 /* Anonymous-Only room */
237 #define QR_ANON2 1024 /* Anonymous-Option room */
238 #define QR_NETWORK 2048 /* Shared network room */
239 #define QR_PREFONLY 4096 /* Preferred status needed to enter */
240 #define QR_READONLY 8192 /* Aide status required to post */
242 Then it returns another '|' symbol, followed by a second set of bits comprised
244 #define QR2_SYSTEM 1 /* System room; hide by default */
245 #define QR2_SELFLIST 2 /* Self-service mailing list mgmt */
247 Other bits may be defined in the future. The listing terminates, as with
248 all listings, with "000" on a line by itself.
250 Starting with version 4.01 and above, floors are supported. The first
251 argument to LKRN should be the number of the floor to list rooms from. Only
252 rooms from this floor will be listed. If no arguments are passed to LKRN, or
253 if the floor number requested is (-1), rooms on all floors will be listed.
255 The third field displayed on each line is the number of the floor the room
256 is on. The LFLR command should be used to associate floor numbers with
259 The fourth field displayed on each line is a "room listing order." Unless
260 there is a compelling reason not to, clients should sort any received room
261 listings by this value.
265 LKRO (List Known Rooms with Old [no new] messages)
267 This follows the same usage and format as LKRN.
270 LZRM (List Zapped RooMs)
272 This follows the same usage and format as LKRN and LKRO.
275 LKRA (List All Known Rooms)
277 Same format. Lists all known rooms, with or without new messages.
280 LRMS (List all accessible RooMS)
282 Again, same format. This command lists all accessible rooms, known and
283 forgotten, with and without new messages. It does not, however, list
284 inaccessible private rooms.
287 LPRM (List all Public RooMs)
289 Again, same format. This command lists all public rooms, and nothing else.
290 Unlike the other list rooms commands, this one can be executed without logging
294 GETU (GET User configuration)
296 This command retrieves the screen dimensions and user options for the
297 currently logged in account. ERROR will be returned if no user is logged
298 in, of course. Otherwise, OK will be returned, followed by four parameters.
299 The first parameter is the user's screen width, the second parameter is the
300 user's screen height, and the third parameter is a bag of bits with the
303 #define US_LASTOLD 16 /* Print last old message with new */
304 #define US_EXPERT 32 /* Experienced user */
305 #define US_UNLISTED 64 /* Unlisted userlog entry */
306 #define US_NOPROMPT 128 /* Don't prompt after each message */
307 #define US_DISAPPEAR 512 /* Use "disappearing msg prompts" */
308 #define US_PAGINATOR 2048 /* Pause after each screen of text */
310 There are other bits, too, but they can't be changed by the user (see below).
313 SETU (SET User configuration)
315 This command does the opposite of SETU: it takes the screen dimensions and
316 user options (which were probably obtained with a GETU command, and perhaps
317 modified by the user) and writes them to the user account. This command
318 should be passed three parameters: the screen width, the screen height, and
319 the option bits (see above).
321 Note that there exist bits here which are not listed in this document. Some
322 are flags that can only be set by Aides or the system administrator. SETU
323 will ignore attempts to toggle these bits. There also may be more user
324 settable bits added at a later date. To maintain later downward compatibility,
325 the following procedure is suggested:
327 1. Execute GETU to read the current flags
328 2. Toggle the bits that we know we can toggle
329 3. Execute SETU to write the flags
331 If we are passed a bit whose meaning we don't know, it's best to leave it
332 alone, and pass it right back to the server. That way we can use an old
333 client on a server that uses an unknown bit without accidentally clearing
334 it every time we set the user's configuration.
339 This command is used to goto a new room. When the user first logs in (login
340 is completed after execution of the PASS command) this command is
341 automatically and silently executed to take the user to the first room in the
342 system (usually called the Lobby).
344 This command can be passed one or two parameters. The first parameter is,
345 of course, the name of the room. Although it is not case sensitive, the
346 full name of the room must be used. Wildcard matching or unique string
347 matching of room names should be the responsibility of the client.
349 Note that the reserved room name "_BASEROOM_" can be passed to the server
350 to cause the goto command to take the user to the first room in the system,
351 traditionally known as the Lobby>. As long as a user is logged in, a
352 GOTO command to _BASEROOM_ is guaranteed to succeed. This is useful to
353 allow client software to return to the base room when it doesn't know
356 There are also two additional reserved room names:
357 "_MAIL_" translates to the system's designated room for e-mail messages.
358 "_BITBUCKET_" goes to whatever room has been chosen for messages
361 The second (and optional) parameter is a password, if one is required for
362 access to the room. This allows for all types of rooms to be accessed via
363 this command: for public rooms, invitation-only rooms to which the user
364 has access, and preferred users only rooms to which the user has access, the
365 room will appear in a room listing. For guess-name rooms, this command
366 will work transparently, adding the room to the user's known room list when
367 it completes. For passworded rooms, access will be denied if the password
368 is not supplied or is incorrect, or the command will complete successfully
369 if the password is correct.
371 The third (and also) optional parameter is a "transient" flag. Normally,
372 when a user enters a private and/or zapped room, the room is added to the
373 user's known rooms list. If the transient flag is set to non-zero, this is
374 called a "transient goto" which causes the user to enter the room without
375 adding the room to the known rooms list.
377 The possible result codes are:
379 OK - The command completed successfully. User is now in the room.
380 (See the list of returned parameters below)
382 ERROR - The command did not complete successfully. Check the second and
383 third positions of the result code to find out what happened:
385 NOT_LOGGED_IN - Of course you can't go there. You didn't log in.
386 PASSWORD_REQUIRED - Either a password was not supplied, or the supplied
387 password was incorrect.
388 NO_SUCH_ROOM - The requested room does not exist.
390 The typical procedure for entering a passworded room would be:
392 1. Execute a GOTO command without supplying any password.
393 2. ERROR+PASSWORD_REQUIRED will be returned. The client now knows that
394 the room is passworded, and prompts the user for a password.
395 3. Execute a GOTO command, supplying both the room name and the password.
396 4. If OK is returned, the command is complete. If, however,
397 ERROR+PASSWORD_REQUIRED is still returned, tell the user that the supplied
398 password was incorrect. The user remains in the room he/she was previously
401 When the command succeeds, these parameters are returned:
402 0. The name of the room
403 1. Number of unread messages in this room
404 2. Total number of messages in this room
405 3. Info flag: set to nonzero if the user needs to read this room's info
406 file (see RINF command below)
407 4. Various flags associated with this room. (See LKRN cmd above)
408 5. The highest message number present in this room
409 6. The highest message number the user has read in this room
410 7. Boolean flag: 1 if this is a Mail> room, 0 otherwise.
411 8. Aide flag: 1 if the user is either the Room Aide for this room, *or* is
412 a regular Aide (this makes access checks easy).
413 9. The number of new Mail messages the user has (useful for alerting the
414 user to the arrival of new mail during a session)
415 10. The floor number this room resides on
416 11. The current "view" for this room (see views.txt for more info)
419 MSGS (get pointers to MeSsaGeS in this room)
421 This command obtains a listing of all the messages in the current room
422 which the client may request. This command may be passed a single parameter:
423 either "all", "old", or "new" to request all messages, only old messages, or
424 new messages. Or it may be passed two parameters: "last" plus a number, in
425 which case that many message pointers will be returned, or "first" plus a
426 number, for the corresponding effect. If no parameters are specified, "all"
429 In Citadel/UX 5.00 and above, the client may also specify "gt" plus a number,
430 to list all messages in the current room with a message number greater than
433 The third argument, valid only in Citadel/UX 5.60 and above, may be either
434 0 or 1. If it is 1, this command behaves differently: before a listing is
435 returned, the client must transmit a list of fields to search for. The field
436 headers are listed below in the writeup for the "MSG0" command.
438 This command can return three possible results. An ERROR code may be returned
439 if no user is currently logged in or if something else went wrong. Otherwise,
440 LISTING_FOLLOWS will be returned, and the listing will consist of zero or
441 more message numbers, one per line. The listing ends, as always, with the
442 string "000" alone on a line by itself. The listed message numbers can be used
443 to request messages from the system. If "search mode" is being used, the
444 server will return START_CHAT_MODE, and the client is expected to transmit
445 the search criteria, and then read the message list.
447 Since this is somewhat complex, here are some examples:
449 Example 1: Read all new messages
452 Server: 100 Message list...
458 Example 2: Read the last five messages
461 Server: 100 Message list...
469 Example 3: Read all messages written by "IGnatius T Foobar"
472 Server: 800 Send template then receive message list
473 Client: from|IGnatius T Foobar
487 Note that in "search mode" the client may specify any number of search
488 criteria. These criteria are applied with an AND logic.
492 MSG0 (read MeSsaGe, mode 0)
494 This is a command used to read the text of a message. "Mode 0" implies that
495 other MSG commands (MSG1, MSG2, etc.) will probably be added later on to read
496 messages in more robust formats. This command should be passed two arguments.
497 The first is the message number of the message being requested. The second
498 argument specifies whether the client wants headers and/or message body:
503 If the request is denied, an ERROR code will be returned. Otherwise, the
504 LISTING_FOLLOWS code will be returned, followed by the contents of the message.
505 The following fields may be sent:
507 type= Formatting type. The currently defined types are:
508 0 = "traditional" Citadel formatting. This means that newlines should be
509 treated as spaces UNLESS the first character on the next line is a space. In
510 other words, only indented lines should generate a newline on the user's screen
511 when the message is being displayed. This allows a message to be formatted to
512 the reader's screen width. It also allows the use of proportional fonts.
513 1 = a simple fixed-format message. The message should be displayed to
514 the user's screen as is, preferably in a fixed-width font that will fit 80
516 4 = MIME format message. The message text is expected to contain a header
517 with the "Content-type:" directive (and possibly others).
519 msgn= The message ID of this message on the system it originated on.
520 path= An e-mailable path back to the user who wrote the message.
522 time= The date and time of the message, in Unix format (the number of
523 seconds since midnight on January 1, 1970, GMT).
525 from= The name of the author of the message.
526 rcpt= If the message is a private e-mail, this is the recipient.
527 room= The name of the room the message originated in.
528 node= The short node name of the system this message originated on.
529 hnod= The long node name of the system this message originated on.
530 zaps= The id/node of a message which this one zaps (supersedes).
532 part= Information about a MIME part embedded in this message.
533 pref= Information about a multipart MIME prefix such as "multipart/mixed"
534 or "multipart/alternative". This will be output immediately prior
535 to the various "part=" lines which make up the multipart section.
536 suff= Information about a multipart MIME suffix. This will be output
537 immediately following the various "part=" lines which make up the
540 text Note that there is no "=" after the word "text". This string
541 signifies that the message text begins on the next line.
544 WHOK (WHO Knows room)
546 This command is available only to Aides. ERROR+HIGHER_ACCESS_REQUIRED will
547 be returned if the user is not an Aide. Otherwise, it returns
548 LISTING_FOLLOWS and then lists, one user per line, every user who has
549 access to the current room.
552 INFO (get server INFO)
554 This command will *always* return LISTING_FOLLOWS and then print out a
555 listing of zero or more strings. Client software should be written to expect
556 anywhere from a null listing to an infinite number of lines, to allow later
557 backward compatibility. The current implementation defines the following
558 parts of the listing:
560 Line 1 - Your unique session ID on the server
561 Line 2 - The node name of the server BBS
562 Line 3 - Human-readable node name of the server BBS
563 Line 4 - The fully-qualified domain name (FQDN) of the server
564 Line 5 - The name of the server software, i.e. "Citadel/UX 4.00"
565 Line 6 - (The revision level of the server code) * 100
566 Line 7 - The geographical location of the BBS (city and state if in the US)
567 Line 8 - The name of the system administrator
568 Line 9 - A number identifying the server type (see below)
569 Line 10 - The text of the system's paginator prompt
570 Line 11 - Floor Flag. 1 if the system supports floors, 0 otherwise.
571 Line 12 - Paging level. 0 if the system only supports inline paging,
572 1 if the system supports "extended" paging (check-only and
573 multiline modes). See the SEXP command for further information.
574 Line 13 - The "nonce" for this session, for support of APOP-style
575 authentication. If this field is present, clients may authenticate
577 Line 14 - Set to nonzero if this server supports the QNOP command.
579 *** NOTE! *** The "server type" code is intended to promote global
580 compatibility in a scenario in which developers have added proprietary
581 features to their servers or clients. We are attempting to avoid a future
582 situation in which users need to keep different client software around for
583 each BBS they use. *Please*, if you are a developer and plan to add
584 proprietary features:
586 -> Your client programs should still be able to utilize servers other than
588 -> Clients other than your own should still be able to utilize your server,
589 even if your proprietary extensions aren't supported.
590 -> Please contact Art Cancro <ajc@uncensored.citadel.org> and obtain a unique
591 server type code, which can be assigned to your server program.
592 -> If you document what you did in detail, perhaps it can be added to a
593 future release of the Citadel/UX program, so everyone can enjoy it. Better
594 yet, just work with the Citadel development team on the main source tree.
596 If everyone follows this scheme, we can avoid a chaotic situation with lots
597 of confusion about which client program works with which server, etc. Client
598 software can simply check the server type (and perhaps the revision level)
599 to determine ahead of time what commands may be utilized.
601 Please refer to "developers.txt" for information on what codes belong to whom.
605 RDIR (Read room DIRectory)
607 Use this command to read the directory of a directory room. ERROR+NOT_HERE
608 will be returned if the room has no directory, or some other error; ERROR +
609 HIGHER_ACCESS_REQUIRED will be returned if the room's directory is not
610 visible and the user does not have Aide or Room Aide privileges; otherwise
611 LISTING_FOLLOWS will be returned, followed by the room's directory. Each
612 line of the directory listing will contain three fields: a filename, the
613 length of the file, and a description.
615 The server message contained on the same line with LISTING_FOLLOWS will
616 contain the name of the system and the name of the directory, such as:
617 uncensored.citadel.org|/usr/bbs/files/my_room_directory
620 SLRP (Set Last-message-Read Pointer)
622 This command marks all messages in the current room as read (seen) up to and
623 including the specified number. Its sole parameter
624 is the number of the last message that has been read. This allows the pointer
625 to be set at any arbitrary point in the room. Optionally, the parameter
626 "highest" may be used instead of a message number, to set the pointer to the
627 number of the highest message in the room, effectively marking all messages
628 in the room as having been read (ala the Citadel <G>oto command).
630 The command will return OK if the pointer was set, or ERROR if something
631 went wrong. If OK is returned, it will be followed by a single argument
632 containing the message number the last-read-pointer was set to.
635 INVT (INViTe a user to a room)
637 This command may only be executed by Aides, or by the room aide for the
638 current room. It is used primarily to add users to invitation-only rooms,
639 but it may also be used in other types of private rooms as well. Its sole
640 parameter is the name of the user to invite.
642 The command will return OK if the operation succeeded, or ERROR if it did
643 not. ERROR+HIGHER_ACCESS_REQUIRED may also be returned if the operation
644 would have been possible if the user had higher access, and ERROR+NOT_HERE
645 may be returned if the room is not a private room.
648 KICK (KICK a user out of a room)
650 This is the opposite of INVT: it is used to kick a user out of a private
651 room. It can also be used to kick a user out of a public room, but the
652 effect will only be the same as if the user <Z>apped the room - a non-stupid
653 user can simply un-zap the room to get back in.
656 GETR (GET Room attributes)
658 This command is used for editing the various attributes associated with a
659 room. A typical "edit room" command would work like this:
660 1. Use the GETR command to get the current attributes
661 2. Change some of them around
662 3. Use SETR (see below) to save the changes
663 4. Possibly also change the room aide using the GETA and SETA commands
665 GETR takes no arguments. It will only return OK if the SETR command will
666 also return OK. This allows client software to tell the user that he/she
667 can't edit the room *before* going through the trouble of actually doing the
668 editing. Possible return codes are:
670 ERROR+NOT_LOGGED_IN - No user is logged in.
671 ERROR+HIGHER_ACCESS_REQUIRED - Not enough access. Typically, only aides
672 and the room aide associated with the current room, can access this command.
673 ERROR+NOT_HERE - Lobby>, Mail>, and Aide> cannot be edited.
674 OK - Command succeeded. Parameters are returned.
676 If OK is returned, the following parameters will be returned as well:
678 0. The name of the room
679 1. The room's password (if it's a passworded room)
680 2. The name of the room's directory (if it's a directory room)
681 3. Various flags (bits) associated with the room (see LKRN cmd above)
682 4. The floor number on which the room resides
683 5. The room listing order
684 6. The default view for the room (see views.txt)
685 7. A second set of flags (bits) associated with the room
688 SETR (SET Room attributes)
690 This command sets various attributes associated with the current room. It
691 should be passed the following arguments:
693 0. The name of the room
694 1. The room's password (if it's a passworded room)
695 2. The name of the room's directory (if it's a directory room)
696 3. Various flags (bits) associated with the room (see LKRN cmd above)
697 4. "Bump" flag (see below)
698 5. The floor number on which the room should reside
699 6. The room listing order
700 7. The default view for the room (see views.txt)
701 8. A second set of flags (buts) associated with the room
703 *Important: You should always use GETR to retrieve the current attributes of
704 the room, then change what you want to change, and then use SETR to write it
705 all back. This is particularly important with respect to the flags: if a
706 particular bit is set, and you don't know what it means, LEAVE IT ALONE and
707 only toggle the bits you want to toggle. This will allow for upward
710 If the room is a private room, you have the option of causing all users who
711 currently have access, to forget the room. If you want to do this, set the
712 "bump" flag to 1, otherwise set it to 0.
717 This command is used to get the name of the Room Aide for the current room.
718 It will return ERROR+NOT_LOGGED_IN if no user is logged in, ERROR if there
719 is no current room, or OK if the command succeeded. Along with OK there will
720 be returned one parameter: the name of the Room Aide.
725 The opposite of GETA, used to set the Room Aide for the current room. One
726 parameter should be passed, which is the name of the user who is to be the
727 new Room Aide. Under Citadel/UX, this command may only be executed by Aides
728 and by the *current* Room Aide for the room. Return codes possible are:
729 ERROR+NOT_LOGGED_IN (Not logged in.)
730 ERROR+HIGHER_ACCESS_REQUIRED (Higher access required.)
731 ERROR+NOT_HERE (No current room, or room cannot be edited.
732 Under Citadel/UX, the Lobby> Mail> and Aide> rooms are non-editable.)
733 OK (Command succeeded.)
736 ENT0 (ENTer message, mode 0)
738 This command is used to enter messages into the system. It accepts four
741 0 - Post flag. This should be set to 1 to post a message. If it is
742 set to 0, the server only returns OK or ERROR (plus any flags describing
743 the error) without reading in a message. Client software should, in fact,
744 perform this operation at the beginning of an "enter message" command
745 *before* starting up its editor, so the user does not end up typing a message
746 in vain that will not be permitted to be saved. If it is set to 2, the
747 server will accept an "apparent" post name if the user is privileged enough.
748 This post name is arg 4.
749 1 - Recipient. This argument is utilized only for private mail messages.
750 It is ignored for public messages. It contains, of course, the name of the
751 recipient of the message.
752 2 - Anonymous flag. This argument is ignored unless the room allows
753 anonymous messages. In such rooms, this flag may be set to 1 to flag a
754 message as anonymous, otherwise 0 for a normal message.
755 3 - Format type. Any valid Citadel/UX format type may be used (this will
756 typically be 0; see the MSG0 command above).
757 4 - Post name. When postflag is 2, this is the name you are posting as.
758 This is an Aide only command.
760 Possible result codes:
761 OK - The request is valid. (Client did not set the "post" flag, so the
762 server will not read in message text.) If the message is an e-mail with
763 a recipient, the text that follows the OK code will contain the exact name
764 to which mail is being sent. The client can display this to the user. The
765 implication here is that the name that the server returns will contain the
766 correct upper and lower case characters. In addition, if the recipient is
767 having his/her mail forwarded, the forwarding address will be returned.
768 SEND_LISTING - The request is valid. The client should now transmit
769 the text of the message (ending with a 000 on a line by itself, as usual).
770 ERROR - Miscellaneous error. (Explanation probably follows.)
771 ERROR + NOT_LOGGED_IN - Not logged in.
772 ERROR + HIGHER_ACCESS_REQUIRED - Higher access is required. An
773 explanation follows, worded in a form that can be displayed to the user.
774 ERROR + NO_SUCH_USER - The specified recipient does not exist.
777 RINF (read Room INFormation file)
779 Each room has associated with it a text file containing a description of
780 the room, perhaps containing its intended purpose or other important
781 information. The info file for the Lobby> (the system's base room) is
782 often used as a repository for system bulletins and the like.
784 This command, which accepts no arguments, is simply used to read the info
785 file for the current room. It will return LISTING_FOLLOWS followed by
786 the text of the message (always in format type 0) if the request can be
787 honored, or ERROR if no info file exists for the current room (which is
788 often the case). Other error description codes may accompany this result.
790 When should this command be used? This is, of course, up to the discretion
791 of client software authors, but in Citadel it is executed in two situations:
792 the first time the user ever enters a room; and whenever the contents of the
793 file change. The latter can be determined from the result of a GOTO command,
794 which will tell the client whether the file needs to be read (see GOTO above).
797 DELE (DELEte a message)
799 Delete a message from the current room. The one argument that should be
800 passed to this command is the message number of the message to be deleted.
801 The return value will be OK if the message was deleted, or an ERROR code.
802 If the delete is successful, the message's reference count is decremented, and
803 if the reference count reaches zero, the message is removed from the message
807 MOVE (MOVE or copy a message to a different room)
809 Move a message to a different room. The two arguments that should be passed
810 to this command are the message number of the message to be deleted, and the
811 name of the target room. If the operation succeeds, the message will be
812 deleted from the current room and moved to the target room. An ERROR code
813 usually means that either the user does not have permission to perform this
814 operation, or that the target room does not exist.
816 In Citadel/UX 5.55 and above, a third argument may be specified: 0 or 1 to
817 designate whether the message should be moved (0) or copied (1) to the target
818 room. In the case of a "copy" operation, the message's reference count is
819 incremented, and a pointer to the message will exist in both the source *and*
820 target rooms. In the case of a "move" operation, the message pointer is
821 deleted from the source room and the reference count remains the same.
824 KILL (KILL current room)
826 This command deletes the current room. It accepts a single argument, which
827 should be nonzero to actually delete the room, or zero to merely check
828 whether the room can be deleted.
830 Once the room is deleted, the current room is undefined. It is suggested
831 that client software immediately GOTO another room (usually _BASEROOM_)
832 after this command completes.
834 Possible return codes:
836 OK - room has been deleted (or, if checking only, request is valid).
837 ERROR+NOT_LOGGED_IN - no user is logged in.
838 ERROR+HIGHER_ACCESS_REQUIRED - not enough access to delete rooms.
839 ERROR+NOT_HERE - this room can not be deleted.
842 CRE8 (CRE[ate] a new room)
844 This command is used to create a new room. Like some of the other
845 commands, it provides a mechanism to first check to see if a room can be
846 created before actually executing the command. CRE8 accepts the following
849 0 - Create flag. Set this to 1 to actually create the room. If it is
850 set to 0, the server merely checks that there is a free slot in which to
851 create a new room, and that the user has enough access to create a room. It
852 returns OK if the client should go ahead and prompt the user for more info,
853 or ERROR or ERROR+HIGHER_ACCESS_REQUIRED if the command will not succeed.
854 1 - Name for new room.
855 2 - Access type for new room:
857 1 - Private; can be entered by guessing the room's name
858 2 - Private; can be entered by knowing the name *and* password
859 3 - Private; invitation only (sometimes called "exclusive")
860 3 - Password for new room (if it is a type 2 room)
861 4 - Floor number on which the room should reside (optional)
862 5 - Set to 1 to avoid automatically gaining access to the created room.
864 If the create flag is set to 1, the room is created (unless something
865 went wrong and an ERROR return is sent), and the server returns OK, but
866 the session is **not** automatically sent to that room. The client still
867 must perform a GOTO command to go to the new room.
870 FORG (FORGet the current room)
872 This command is used to forget (zap) the current room. For those not
873 familiar with Citadel, this terminology refers to removing the room from
874 a user's own known rooms list, *not* removing the room itself. After a
875 room is forgotten, it no longer shows up in the user's known room list,
876 but it will exist in the user's forgotten room list, and will return to the
877 known room list if the user goes to the room (in Citadel, this is
878 accomplished by explicitly typing the room's name in a <.G>oto command).
880 The command takes no arguments. If the command cannot execute for any
881 reason, ERROR will be returned. ERROR+NOT_LOGGED_IN or ERROR+NOT_HERE may
882 be returned as they apply.
884 If the command succeeds, OK will be returned. At this point, the current
885 room is **undefined**, and the client software is responsible for taking
886 the user to another room before executing any other room commands (usually
887 this will be _BASEROOM_ since it is always there).
890 MESG (read system MESsaGe)
892 This command is used to display system messages and/or help files. The
893 single argument it accepts is the name of the file to display. IT IS CASE
894 SENSITIVE. Citadel/UX looks for these files first in the "messages"
895 subdirectory and then in the "help" subdirectory.
897 If the file is found, LISTING_FOLLOWS is returned, followed by a pathname
898 to the file being displayed. Then the message is printed, in format type 0
899 (see MSG0 command for more information on this). If the file is not found,
902 There are some "well known" names of system messages which client software
903 may expect most servers to carry:
905 hello - Welcome message, to be displayed before the user logs in.
906 changepw - To be displayed whenever the user is prompted for a new
907 password. Warns about picking guessable passwords and such.
908 register - Should be displayed prior to the user entering registration.
909 Warnings about not getting access if not registered, etc.
910 help - Main system help file.
911 goodbye - System logoff banner; display when user logs off.
912 roomaccess - Information about how public rooms and different types of
913 private rooms function with regards to access.
914 unlisted - Tells users not to choose to be unlisted unless they're
915 really paranoid, and warns that aides can still see
916 unlisted userlog entries.
918 Citadel/UX provides these for the Citadel/UX Unix text client. They are
919 probably not very useful for other clients:
921 mainmenu - Main menu (when in idiot mode).
926 saveopt - Options to save a message, abort, etc.
927 entermsg - Displayed just before a message is entered, when in
931 GNUR (Get Next Unvalidated User)
933 This command shows the name of a user that needs to be validated. If there
934 are no unvalidated users, OK is returned. Otherwise, MORE_DATA is returned
935 along with the name of the first unvalidated user the server finds. All of
936 the usual ERROR codes may be returned as well (for example, if the user is
937 not an Aide and cannot validate users).
939 A typical "Validate New Users" command would keep executing this command,
940 and then validating each user it returns, until it returns OK when all new
941 users have been validated.
944 GREG (Get REGistration for user)
946 This command retrieves the registration info for a user, whose name is the
947 command's sole argument. All the usual error messages can be returned. If
948 the command succeeds, LISTING_FOLLOWS is returned, followed by the user's name
949 (retrieved from the userlog, with the right upper and lower case etc.) The
950 contents of the listing contains one field per line, followed by the usual
951 000 on the last line.
953 The following lines are defined. Others WILL be added in the futre, so all
954 software should be written to read the lines it knows about and then ignore
960 Line 4: Street address or PO Box
961 Line 5: City/town/village/etc.
962 Line 6: State/province/etc.
964 Line 8: Telephone number
966 Line 10: Internet e-mail address
969 Users without Aide privileges may retrieve their own registration using
970 this command. This can be accomplished either by passing the user's own
971 name as the argument, or the string "_SELF_". The command will always
972 succeed when used in this manner, unless no user is logged in.
977 This command is used to validate users. Obviously, it can only be executed
978 by users with Aide level access. It should be passed two parameters: the
979 name of the user to validate, and the desired access level
981 If the command succeeds, OK is returned. The user's access level is changed
982 and the "need validation" bit is cleared. If the command fails for any
983 reason, ERROR, ERROR+NO_SUCH_USER, or ERROR+HIGHER_ACCESS_REQUIRED will be
987 EINF (Enter INFo file for room)
989 Transmit the info file for the current room with this command. EINF uses
990 a boolean flag (1 or 0 as the first and only argument to the command) to
991 determine whether the client actually wishes to transmit a new info file, or
992 is merely checking to see if it has permission to do so.
994 If the command cannot succeed, it returns ERROR.
995 If the client is only checking for permission, and permission will be
996 granted, OK is returned.
997 If the client wishes to transmit the new info file, SEND_LISTING is
998 returned, and the client should transmit the text of the info file, ended
999 by the usual 000 on a line by itself.
1004 This is a simple user listing. It always succeeds, returning
1005 LISTING_FOLLOWS followed by zero or more user records, 000 terminated. The
1006 fields on each line are as follows:
1011 4. Date/time of last login (Unix format)
1014 7. Password (listed only if the user requesting the list is an Aide)
1016 Unlisted entries will also be listed to Aides logged into the server, but
1017 not to ordinary users.
1020 REGI (send REGIstration)
1022 Clients will use this command to transmit a user's registration info. If
1023 no user is logged in, ERROR+NOT_LOGGED_IN is returned. Otherwise,
1024 SEND_LISTING is returned, and the server will expect the following information
1025 (terminated by 000 on a line by itself):
1028 Line 2: Street address or PO Box
1029 Line 3: City/town/village/etc.
1030 Line 4: State/province/etc.
1032 Line 6: Telephone number
1033 Line 7: e-mail address
1037 CHEK (CHEcK various things)
1039 When logging in, there are various things that need to be checked. This
1040 command will return ERROR+NOT_LOGGED_IN if no user is logged in. Otherwise
1041 it returns OK and the following parameters:
1043 0: Number of new private messages in Mail>
1044 1: Nonzero if the user needs to register
1045 2: (Relevant to Aides only) Nonzero if new users require validation
1048 DELF (DELete a File)
1050 This command deletes a file from the room's directory, if there is one. The
1051 name of the file to delete is the only parameter to be supplied. Wildcards
1052 are not acceptable, and any slashes in the filename will be converted to
1053 underscores, to prevent unauthorized access to neighboring directories. The
1054 possible return codes are:
1056 OK - Command succeeded. The file was deleted.
1057 ERROR+NOT_LOGGED_IN - Not logged in.
1058 ERROR+HIGHER_ACCESS_REQUIRED - Not an Aide or Room Aide.
1059 ERROR+NOT_HERE - There is no directory in this room.
1060 ERROR+FILE_NOT_FOUND - Requested file was not found.
1065 This command is similar to DELF, except that it moves a file (and its
1066 associated file description) to another room. It should be passed two
1067 parameters: the name of the file to move, and the name of the room to move
1068 the file to. All of the same return codes as DELF may be returned, and also
1069 one additional one: ERROR+NO_SUCH_ROOM, which means that the target room
1070 does not exist. ERROR+NOT_HERE could also mean that the target room does
1071 not have a directory.
1074 NETF (NETwork send a File)
1076 This command is similar to MOVF, except that it attempts to send a file over
1077 the network to another system. It should be passed two parameters: the name
1078 of the file to send, and the node name of the system to send it to. All of
1079 the same return codes as MOVF may be returned, except for ERROR+NO_SUCH_ROOM.
1080 Instead, ERROR+NO_SUCH_SYSTEM may be returned if the name of the target
1083 The name of the originating room will be sent along with the file. Most
1084 implementations will look for a room with the same name at the receiving end
1085 and attempt to place the file there, otherwise it goes into a bit bucket room
1086 for miscellaneous files. This is, however, beyond the scope of this document;
1087 see elsewhere for more details.
1090 RWHO (Read WHO's online)
1092 Displays a list of all users connected to the server. No error codes are
1093 ever returned. LISTING_FOLLOWS will be returned, followed by zero or more
1094 lines containing the following three fields:
1096 0 - Session ID. Citadel/UX fills this with the pid of a server program.
1098 2 - The name of the room the user is currently in. This field might not
1099 be displayed (for example, if the user is in a private room) or it might
1100 contain other information (such as the name of a file the user is
1102 3 - (server v4.03 and above) The name of the host the client is connecting
1103 from, or "localhost" if the client is local.
1104 4 - (server v4.04 and above) Description of the client software being used
1105 5 - The last time, locally to the server, that a command was received from
1106 this client (Note: NOOP's don't count)
1107 6 - The last command received from a client. (NOOP's don't count)
1108 7 - Session flags. These are: + (spoofed address), - (STEALTH mode), *
1109 (posting) and . (idle).
1110 8 - Actual user name, if user name is masqueraded and viewer is an Aide.
1111 9 - Actual room name, if room name is masqueraded and viewer is an Aide.
1112 10 - Actual host name, if host name is masqueraded and viewer is an Aide.
1114 The listing is terminated, as always, with the string "000" on a line by
1118 OPEN (OPEN a file for download)
1120 This command is used to open a file for downloading. Only one download
1121 file may be open at a time. The only argument to this command is the name
1122 of the file to be opened. The user should already be in the room where the
1123 file resides. Possible return codes are:
1126 ERROR+NOT_HERE (no directory in this room)
1127 ERROR+FILE_NOT_FOUND (could not open the file)
1131 If the file is successfully opened, OK will be returned, along with the
1132 size (in bytes) of the file, the time of last modification (if applicable),
1133 the filename (if known), and the MIME type of the file (if known).
1136 CLOS (CLOSe the download file)
1138 This command is used to close the download file. It returns OK if the
1139 file was successfully closed, or ERROR if there wasn't any file open in the
1143 READ (READ from the download file)
1145 Two arguments are passed to this command. The first is the starting position
1146 in the download file, and the second is the total number of bytes to be
1147 read. If the operation can be performed, BINARY_FOLLOWS will be returned,
1148 along with the number of bytes to follow. Then, immediately following the
1149 newline, will be that many bytes of binary data. The client *must* read
1150 exactly that number of bytes, otherwise the client and server will get out
1153 If the operation cannot be performed, any of the usual error codes will be
1157 UOPN (OPeN a file for Uploading)
1159 This command is similar to OPEN, except that this one is used when the
1160 client wishes to upload a file to the server. The first argument is the name
1161 of the file to create, and the second argument is a one-line comment
1162 describing the contents of the file. Only one upload file may be open at a
1163 time. Possible return codes are:
1166 ERROR+NOT_HERE (no directory in this room)
1167 ERROR+FILE_NOT_FOUND (a name must be specified)
1168 ERROR (miscellaneous errors)
1169 ERROR+ALREADY_EXISTS (a file with the same name already exists)
1172 If OK is returned, the command has succeeded and writes may be performed.
1175 UCLS (CLoSe the Upload file)
1177 Close the file opened with UOPN. An argument of "1" should be passed to
1178 this command to close and save the file; otherwise, the transfer will be
1179 considered aborted and the file will be deleted. This command returns OK
1180 if the operation succeeded or ERROR if it did not.
1183 WRIT (WRITe to the upload file)
1185 If an upload file is open, this command may be used to write to it. The
1186 argument passed to this command is the number of bytes the client wishes to
1187 transmit. An ERROR code will be returned if the operation cannot be
1190 If the operation can be performed, SEND_BINARY will be returned, followed
1191 by the number of bytes the server is expecting. The client must then transmit
1192 exactly that number of bytes. Note that in the current implementation, the
1193 number of bytes the server is expecting will always be the number of bytes
1194 the client requested to transmit, but the client software should never assume
1195 that this will always happen, in case changes are made later.
1198 QUSR (Query for a USeR)
1200 This command is used to check to see if a particular user exists. The only
1201 argument to this command is the name of the user being searched for. If
1202 the user exists, OK is returned, along with the name of the user in the userlog
1203 (so the client software can learn the correct upper/lower casing of the name
1204 if necessary). If the user does not exist, ERROR+NO_SUCH_USER is returned.
1205 No login or current room is required to utilize this command.
1208 OIMG (Open an IMaGe file)
1210 Open an image (graphics) file for downloading. Once opened, the file can be
1211 read as if it were a download file. This implies that an image and a download
1212 cannot be opened at the same time. OIMG returns the same result codes as OPEN.
1214 All images will be in GIF (Graphics Interchange Format). In the case of
1215 Citadel/UX, the server will convert the supplied filename to all lower case,
1216 append the characters ".gif" to the filename, and look for it in the "images"
1217 subdirectory. As with the MESG command, there are several "well known"
1218 images which are likely to exist on most servers:
1220 hello - "Welcome" graphics to be displayed alongside MESG "hello"
1221 goodbye - Logoff banner graphics to be displayed alongside MESG "goodbye"
1222 background - Background image (usually tiled) for graphical clients
1224 The following "special" image names are defined in Citadel/UX server version
1227 _userpic_ - Picture of a user (send the username as the second argument)
1228 _floorpic_ - A graphical floor label (send the floor number as the second
1229 argument). Clients which request a floor picture will display
1230 the picture *instead* of the floor name.
1231 _roompic_ - A graphic associated with the *current* room. Clients which
1232 request a room picture will display the picture in *addition*
1233 to the room name (i.e. it's used for a room banner, as
1234 opposed to the floor picture's use in a floor listing).
1237 NETP (authenticate as network session with system NET Password)
1239 This command is used by client software to identify itself as a transport
1240 session for IGnet/Open BBS to BBS networking. It should be called with
1241 two arguments: the node name of the calling system, and the system net
1242 password for the server. If the authentication succeeds, NETP will return
1243 OK, otherwise, it returns ERROR.
1246 NUOP (Network Upload OPen file)
1248 Open a network spool file for uploading. The client must have already
1249 identified itself as a network session using the NETP command. If the command
1250 returns OK, the client may begin transmitting IGnet/Open spool data using
1251 a series of WRIT commands. When a UCLS command is issued, the spooled data
1252 is entered into the BBS if the argument to UCLS is 1 or discarded if the
1253 argument to UCLS is 0. If the client has not authenticated itself with a
1254 NETP command, ERROR+HIGHER_ACCESS_REQUIRED will be returned.
1257 NDOP (Network Download OPen file)
1259 Open a network spool file for downloading. The client must have already
1260 identified itself as a network session using the NETP command. If the command
1261 returns OK, the client may begin receiving IGnet/Open spool data using
1262 a series of READ commands. When a CLOS command is issued, the spooled data
1263 is deleted from the server and may not be read again. If the client has not
1264 authenticated itself with a NETP command, ERROR+HIGHER_ACCESS_REQUIRED will
1268 LFLR (List all known FLooRs)
1270 On systems supporting floors, this command lists all known floors. The
1271 command accepts no parameters. It will return ERROR+NOT_LOGGED_IN if no
1272 user is logged in. Otherwise it returns LISTING_FOLLOWS and a list of
1273 the available floors, each line consisting of three fields:
1275 1. The floor number associated with the floor
1276 2. The name of the floor
1277 3. Reference count (number of rooms on this floor)
1280 CFLR (Create a new FLooR)
1282 This command is used to create a new floor. It should be passed two
1283 arguments: the name of the new floor to be created, and a 1 or 0 depending
1284 on whether the client is actually creating a floor or merely checking to
1285 see if it has permission to create the floor. The user must be logged in
1286 and have Aide privileges to create a floor.
1288 If the command succeeds, it will return OK followed by the floor number
1289 associated with the new floor. Otherwise, it will return ERROR (plus perhaps
1290 HIGHER_ACCESS_REQUIRED, ALREADY_EXISTS, or INVALID_FLOOR_OPERATION)
1291 followed by a description of why the command failed.
1296 This command is used to delete a floor. It should be passed two
1297 argument: the *number* of the floor to be deleted, and a 1 or 0 depending
1298 on whether the client is actually deleting the floor or merely checking to
1299 see if it has permission to delete the floor. The user must be logged in
1300 and have Aide privileges to delete a floor.
1302 Floors that contain rooms may not be deleted. If there are rooms on a floor,
1303 they must be either deleted or moved to different floors first. This implies
1304 that the Main Floor (floor 0) can never be deleted, since Lobby>, Mail>, and
1305 Aide> all reside on the Main Floor and cannot be deleted.
1307 If the command succeeds, it will return OK. Otherwise it will return
1308 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1309 followed by a description of why the command failed.
1314 Edit the parameters of a floor. The client may pass one or more parameters
1317 1. The number of the floor to be edited
1318 2. The desired new name
1320 More parameters may be added in the future. Any parameters not passed to
1321 the server will remain unchanged. A minimal command would be EFLR and a
1322 floor number -- which would do nothing. EFLR plus the floor number plus a
1323 floor name would change the floor's name.
1325 If the command succeeds, it will return OK. Otherwise it will return
1326 ERROR (plus perhaps HIGHER_ACCESS_REQUIRED or INVALID_FLOOR_OPERATION)
1329 IDEN (IDENtify the client software)
1331 The client software has the option to identify itself to the server.
1332 Currently, the server does nothing with this information except to write
1333 it to the syslog to satisfy the system administrator's curiosity. Other
1334 uses might become apparent in the future.
1336 The IDEN command should contain five fields: a developer ID number (same as
1337 the server developer ID numbers in the INFO command -- please obtain one if
1338 you are a new developer), a client ID number (which does not have to be
1339 globally unique - only unique within the domain of the developer number),
1340 a version number, a free-form text string describing the client, and the name
1341 of the host the user is located at.
1343 It is up to the server to determine whether to accept the host name or to
1344 use the host name it has detected itself. Generally, if the client is
1345 running on a trusted host (either localhost or a well-known publically
1346 accessible client) it should use the host name transmitted by IDEN,
1347 otherwise it should use the host name it has detected itself.
1349 IDEN always returns OK, but since that's the only way it ever returns
1350 there's no point in checking the result code.
1353 IPGM (identify as an Internal ProGraM)
1355 IPGM is a low-level command that should not be used by normal user clients.
1356 It is used for various utilities to communicate with the server on the same
1357 host. For example, the "sendcommand" utility logs onto the server as an
1358 internal program in order to run arbitrary server commands. Since user clients
1359 do not utilize this command (or any of its companion commands), developers
1360 writing Citadel-compatible servers need not implement it.
1362 The sole argument to IPGM is the system's internal program password. This
1363 password is generated by the setup program and stored in the config file.
1364 Since internal programs have access to the config file, they know the correct
1367 IPGM returns OK for a correct authentication or ERROR otherwise.
1370 CHAT (enter CHAT mode)
1372 This command functions differently from every other command in the system. It
1373 is used to implement multi-user chat. For this to function, a new transfer
1374 mode, called START_CHAT_MODE, is implemented. If a client does not support
1375 chat mode, it should never send a CHAT command!
1377 In chat mode, messages may arrive asynchronously from the server at any
1378 time. The client may send messages at any time. This allows the arrival of
1379 messages without the client having to poll for them. Arriving messages will
1380 be of the form "user|message", where the "user" portion is, of course, the
1381 name of the user sending the message, and "message" is the message text.
1383 Chat mode ends when the server says it ends. The server will signal the end
1384 of chat mode by transmitting "000" on a line by itself. When the client reads
1385 this line, it must immediately exit from chat mode without sending any
1386 further traffic to the server. The next transmission sent to the server
1387 will be a regular server command.
1389 The Citadel/UX server understands the following commands:
1390 /quit - Exit from chat mode (causes the server to do an 000 end)
1391 /who - List users currently in chat
1392 /whobbs - List users currently in chat and on the bbs
1393 /me - Do an irc-style action.
1394 /join - Join a new "room" in which all messages are only heard by
1395 people in that room.
1396 /msg - /msg <user> <msg> will send the msg to <user> only.
1397 /help - Print help information
1398 NOOP - Do nothing (silently)
1400 Any other non-empty string is treated as message text and will be broadcast
1401 to other users currently in chat.
1404 SEXP (Send EXPress messages)
1406 This is one of two commands which implement "express messages" (also known
1407 as "paging"). An express message is a near-real-time message sent from one
1408 logged in user to another. When an express message is sent, it will be
1409 displayed the next time the target user executes a PEXP or GEXP command.
1411 The SEXP command accepts two arguments: the name of the user to send the
1412 message to, and the text of the message. If the message is successfully
1413 transmitted, OK is returned. If the target user is not logged in or if
1414 anything else goes wrong, ERROR is returned.
1416 If the server supports extended paging, sending a zero-length message
1417 merely checks for the presence of the requested user without actually sending
1418 a message. Sending a message consisting solely of a "-" (hyphen) will cause
1419 the server to return SEND_LISTING if the requested user is logged in, and the
1420 client can then transmit a multi-line page.
1422 The reserved name "broadcast" may be used instead of a user name, to
1423 broadcast an express message to all users currently connected to the server.
1425 Do be aware that if an express message is transmitted to a user who is logged
1426 in using a client that does not check for express messages, the message will
1430 PEXP (Print EXPress messages) ***DEPRECATED***
1432 This command is deprecated; it will eventually disappear from the protocol and
1433 its use is not recommended. Please use the GEXP command instead.
1435 Called without any arguments, PEXP simply dumps out the contents
1436 of any waiting express messages. It returns ERROR if there is a problem,
1437 otherwise it returns LISTING_FOLLOWS followed by all messages.
1439 So how does the client know there are express messages waiting? It could
1440 execute a random PEXP every now and then. Or, it can check the byte in
1441 server return code messages, between the return code and the parameters. In
1442 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1443 an "*" in this position to signify the presence of waiting express messages.
1446 EBIO (Enter BIOgraphy)
1448 Transmit to the server a free-form text file containing a little bit of
1449 information about the user for other users to browse. This is typically
1450 referred to as a 'bio' online. EBIO returns SEND_LISTING if it succeeds,
1451 after which the client is expected to transmit the file, or any of the usual
1452 ERROR codes if it fails.
1455 RBIO (Read BIOgraphy)
1457 Receive from the server a named user's bio. This command should be passed
1458 a single argument - the name of the user whose bio is requested. RBIO returns
1459 LISTING_FOLLOWS plus the bio file if the user exists and has a bio on file.
1460 The return has the following parameters: the user name, user number, access
1461 level, date of last call, times called, and messages posted. This command
1462 returns ERROR+NO_SUCH_USER if the named user does not exist.
1464 RBIO no longer considers a user with no bio on file to be an error condition.
1465 It now returns a message saying the user has no bio on file as the text of the
1466 bio. This allows newer servers to operate with older clients.
1469 STEL (enter STEaLth mode)
1471 When in "stealth mode," a user will not show up in the "Who is online"
1472 listing (the RWHO server command). Only Aides may use stealth mode. The
1473 STEL command accepts one argument: a 1 indicating that the user wishes to
1474 enter stealth mode, or a 0 indicating that the user wishes to exit stealth
1475 mode. STEL returns OK if the command succeeded, ERROR+NOT_LOGGED_IN if no
1476 user is logged in, or ERROR+HIGHER_ACCESS_REQUIRED if the user is not an Aide;
1477 followed by a 1 or 0 indicating the new state.
1479 If any value other than 1 or 0 is sent by the client, the server simply
1480 replies with 1 or 0 to indicate the current state without changing it.
1482 The STEL command also makes it so a user does not show up in the chat room
1486 LBIO (List users who have BIOs on file)
1488 This command is self-explanatory. Any user who has used EBIO to place a bio
1489 on file is listed. LBIO almost always returns LISTING_FOLLOWS followed by
1490 this listing, unless it experiences an internal error in which case ERROR
1494 MSG2 (read MeSsaGe, mode 2)
1496 MSG2 follows the same calling convention as MSG0. The difference between
1497 the two commands is that MSG2 outputs messages in standard RFC822 format
1498 rather than in Citadel/UX proprietary format.
1500 This command was implemented in order to make various gateway programs
1501 easier to implement, and to provide some sort of multimedia support in the
1502 future. Keep in mind that when this command is used, all messages will be
1503 output in fixed 80-column format.
1506 MSG3 (read MeSsaGe, mode 3 -- internal command)
1508 MSG3 is for use by internal programs only and should not be utilized by
1509 user-mode clients. It does require IPGM authentication. MSG3 follows the
1510 same calling convention as the other MSG commands, but upon success returns
1511 BINARY_FOLLOWS followed by a data block containing the _raw_ message format
1515 TERM (TERMinate another session)
1517 In a multithreaded environment, it sometimes becomes necessary to terminate
1518 a session that is unusable for whatever reason. The TERM command performs
1519 this task. Naturally, only Aides can execute TERM. The command should be
1520 called with a single argument: the session ID (obtained from an RWHO command)
1521 of the session to be terminated.
1523 TERM returns OK if the session was terminated, or ERROR otherwise. Note that
1524 a client program is prohibited from terminating the session it is currently
1530 DOWN (shut DOWN the server)
1532 This command, which may only be executed by an Aide, immediately shuts down
1533 the server. It is only implemented on servers on which such an operation is
1534 possible, such as a multithreaded Citadel engine. The server does not restart.
1535 DOWN returns OK if the user is allowed to shut down the server, in which case
1536 the client program should expect the connection to be immediately broken.
1539 SCDN (Schedule or Cancel a shutDowN)
1541 SCDN sets or clears the "scheduled shutdown" flag. Pass this command a 1 or
1542 0 to respectively set or clear the flag. When the "scheduled shutdown" flag is
1543 set, the server will be shut down when there are no longer any users logged in.
1544 Any value other than 0 or 1 will not change the flag, only report its state.
1545 No users will be kicked off the system, and in fact the server is still
1546 available for new connections. The command returns ERROR if it fails;
1547 otherwise, it returns OK followed by a number representing the current state
1551 EMSG (Enter a system MeSsaGe)
1553 This is the opposite of the MESG command - it allows the creation and editing
1554 of system messages. The only argument passed to EMSG is the name of the
1555 file being transmitted. If the file exists in any system message directory
1556 on the server it will be overwritten, otherwise a new file is created. EMSG
1557 returns SEND_LISTING on success or ERROR+HIGHER_ACCESS_REQUIRED if the user
1560 Typical client software would use MESG to retrieve any existing message into
1561 an edit buffer, then present an editor to the user and run EMSG if the changes
1565 UIMG (Upload an IMaGe file)
1567 UIMG is complemenary to OIMG; it is used to upload an image to the server.
1568 The first parameter supplied to UIMG should be 0 if the client is only checking
1569 for permission to upload, or 1 if the client is actually attempting to begin
1570 the upload operation. The second argument is the name of the file to be
1571 transmitted. In Citadel/UX, the filename is converted to all lower case,
1572 appended with the characters ".gif", and stored in the "images" directory.
1574 UIMG returns OK if the client has permission to perform the requested upload,
1575 or ERROR+HIGHER_ACCESS_REQUIRED otherwise. If the client requested to begin
1576 the operation (first parameter set to 1), an upload file is opened, and the
1577 client should begin writing to it with WRIT commands, then close it with a
1580 The supplied filename should be one of:
1582 -> _userpic_ (Server will attempt to write to the user's online photo)
1583 -> Any of the "well known" filenames described in the writeup for the
1587 HCHG (Hostname CHanGe)
1589 HCHG is a command, usable by any user, that allows a user to change their RWHO
1590 host value. This will mask a client's originating hostname from normal
1591 users; access level 6 and higher can see, in an extended wholist, the actual
1592 hostname the user originates from.
1594 The format of an HCHG command is:
1598 If a HCHG command is successful, the value OK (200) is returned.
1601 RCHG (Roomname CHanGe)
1603 RCHG is a command, usable by any user, that allows a user to change their RWHO
1604 room value. This will mask a client's roomname from normal users; access
1605 level 6 and higher can see, in an extended wholist, the actual room the user
1608 The format of an RCHG command is:
1612 If a RCHG command is successful, the value OK (200) is returned.
1615 UCHG (Username CHanGe)
1617 UCHG is an aide-level command which allows an aide to effectively change their
1618 username. If this value is blank, the user goes into stealth mode (see
1620 will show up as being from the real username in this mode, however. In
1621 addition, the RWHO listing will include both the spoofed and real usernames.
1623 The format of an UCHG command is:
1627 If a UCHG command is successful, the value OK (200) is returned.
1630 TIME (get server local TIME)
1632 TIME returns OK followed by the current time measured in seconds since
1633 00:00:00 GMT, Jan 1, 1970 (standard Unix format).
1635 This is used in allowing a client to calculate idle times.
1638 AGUP (Administrative Get User Parameters)
1639 ASUP (Administrative Set User Parameters)
1641 These commands are only executable by Aides and by server extensions running
1642 at system-level. They are used to get/set any and all parameters relating to
1643 a user account. AGUP requires only one argument: the name of the user in
1644 question. SGUP requires all of the parameters to be set. The parameters are
1645 as follows, and are common to both commands:
1649 2 - Flags (see citadel.h)
1654 7 - Timestamp of last call
1655 8 - Purge time (in days) for this user (or 0 to use system default)
1657 Upon success, AGUP returns OK followed by all these parameters, and ASUP
1658 simply returns OK. If the client has insufficient access to perform the
1659 requested operation, ERROR+HIGHER_ACCESS_REQUIRED is returned. If the
1660 requested user does not exist, ERROR+NO_SUCH_USER is returned.
1664 GPEX (Get Policy for message EXpiration)
1666 Returns the policy of the current room, floor, or site regarding the automatic
1667 purging (expiration) of messages. The following policies are available:
1668 0 - Fall back to the policy of the next higher level. If this is a room,
1669 use the floor's default policy. If this is a floor, use the system
1670 default policy. This is an invalid value for the system policy.
1671 1 - Do not purge messages automatically.
1672 2 - Purge by message count. (Requires a value: number of messages)
1673 3 - Purge by message age. (Requires a value: number of days)
1675 The format of this command is: GPEX <which>
1676 The value of <which> must be one of: "room" "floor" "site"
1678 If successful, GPEX returns OK followed by <policy>|<value>.
1682 SPEX (Set Policy for message EXpiration)
1684 Sets the policy of the current room, floor, or site regarding the automatic
1685 purging (expiration) of messages. See the writeup for the GPEX command for
1686 the list of available policies.
1688 The format of this command is: SPEX <which>|<policy>|<value>
1689 The value of <which> must be one of: "room" "floor" "site"
1691 If successful, GPEX returns OK; otherwise, an ERROR code is returned.
1695 CONF (get or set global CONFiguration options)
1697 Retrieves or sets various system-wide configuration and policy options. This
1698 command is only available to Aides. The sole parameter accepted is a command,
1699 which should be either GET or SET. If the GET command succeeds, CONF will
1700 return LISTING_FOLLOWS followed by the fields described below, one line at a
1701 time. If the SET command succeeds, CONF will return SEND_LISTING and expect
1702 the fields described below, one line at a time (don't worry about other fields
1703 being added in the future; if a 'short' configuration list is sent, the missing
1704 values at the end will be left unchanged on the system). If either command
1705 fails for any reason, ERROR is returned.
1707 The configuration lines are as follows:
1710 2. Fully qualified domain name
1711 3. Human-readable node name
1712 4. Landline telephone number of this system
1713 5. Flag (0 or 1) - creator of private room automatically becomes room aide
1714 6. Server connection idle timeout (in seconds)
1715 7. Initial access level for new users
1716 8. Flag (0 or 1) - require registration for new users
1717 9. Flag (0 or 1) - automatically move Problem User messages to twit room
1718 10. Name of twit room
1719 11. Text of <more> prompt
1720 12. Flag (0 or 1) - restrict access to Internet mail
1721 13. Geographic location of this system
1722 14. Name of the system administrator
1723 15. Number of maximum concurrent sessions allowed on the server
1724 16. Password for server-to-server networking
1725 17. Default purge time (in days) for users
1726 18. Default purge time (in days) for rooms
1727 19. Name of room to log express messages to (or a zero-length name for none)
1728 20. Access level required to create rooms
1729 21. Maximum message length which may be entered into the system
1730 22. Minimum number of worker threads
1731 23. Maximum number of worker threads
1732 24. Port number for POP3 service
1733 25. Port number for SMTP service
1735 27. Flag (0 or 1) - allow Aides to zap (forget) rooms
1736 28. Port number for IMAP service
1737 29. How often (in seconds) to run the networker
1739 CONF also accepts two additional commands: GETSYS and PUTSYS followed by an
1740 arbitrary MIME type (such as application/x-citadel-internet-config) which
1741 provides a means of storing generic configuration data in the Global System
1742 Configuration room without the need to add extra get/set commands to the
1746 EXPI (EXPIre system objects)
1748 Begins purge operations for objects which, according to site policy, are
1749 "old" and should be removed. EXPI should be called with one argument, one of:
1751 "messages" (purge old messages out of each room)
1752 "users" (purge old users from the userlog)
1753 "rooms" (remove rooms which have not been posted in for some time)
1754 "visits" (purge dereferenced user/room relationship records)
1756 EXPI returns OK (probably after a long delay while it does its work) if it
1757 succeeds; otherwise it returns an ERROR code.
1759 This command is probably temporary, until we can work some sort of scheduler
1760 into the system. It is implemented in the serv_expire module.
1764 MSG4 (read MeSsaGe, mode 4 -- output in preferred MIME format)
1766 This is the equivalent of MSG0, except it's a bit smarter about messages in
1767 rich text formats. Immediately following the "text" directive, the server
1768 will output RFC822-like MIME part headers such as "Content-type:" and
1769 "Content-length:". MIME formats are chosen and/or converted based on the
1770 client's preferred format settings, which are set using the MSGP command,
1775 MSGP (set MeSsaGe Preferred MIME format)
1777 Client tells the server what MIME content types it knows how to handle, and
1778 the order in which it prefers them. This is similar to an HTTP "Accept:"
1781 The parameters to a MSGP command are the client's acceptable MIME content
1782 types, in the order it prefers them (from most preferred to least preferred).
1783 For example: MSGP text/html|text/plain
1785 The MSGP command always returns OK.
1789 OPNA (OPeN Attachment)
1791 Opens, as a download file, a component of a MIME-encoded message. The two
1792 parameters which must be passed to this command are the message number and the
1793 name of the desired section. If the message or section does not exist, an
1794 appropriate ERROR code will be returned; otherwise, if the open is successful,
1795 this command will succeed returning the same information as an OPEN command.
1798 GEXP (Get EXPress messages)
1800 This is a more sophisticated way of retrieving express messages than the old
1801 PEXP method. If there are no express messages waiting, PEXP returns ERROR;
1802 otherwise, it returns LISTING_FOLLOWS and the following arguments:
1804 0 - a boolean value telling the client whether there are any additional
1805 express messages waiting following this one
1806 1 - a Unix-style timestamp
1807 2 - flags (see server.h for more info)
1808 3 - the name of the sender
1809 4 - the node this message originated on (for future support of PIP, ICQ, etc.)
1811 The text sent to the client will be the body of the express message.
1813 So how does the client know there are express messages waiting? It could
1814 execute a random GEXP every now and then. Or, it can check the byte in
1815 server return code messages, between the return code and the parameters. In
1816 much the same way as FTP uses "-" to signify a continuation, Citadel uses
1817 an "*" in this position to signify the presence of waiting express messages.
1820 FSCK (check message base reference counts)
1822 Verify, via the long way, that all message referenmce counts are correct. If
1823 the user has permission to do this then LISTING_FOLLOWS is returned, followed
1824 by a transcript of the run. Otherwise ERROR is returned.
1827 DEXP (Disable EXPress messages)
1829 DEXP sets or clears the "disable express messages" flag. Pass this command a
1830 1 or 0 to respectively set or clear the flag. When the "disable express
1831 messages" flag is set, no one except Aides may send the user express messages.
1832 Any value other than 0 or 1 will not change the flag, only report its state.
1833 The command returns ERROR if it fails; otherwise, it returns OK followed by a
1834 number representing the current state of the flag.
1837 REQT (REQuest client Termination)
1839 Request that the specified client (or all clients) log off. Aide level
1840 access is required to run this command, otherwise ERROR+HIGHER_ACCESS_REQUIRED
1843 The REQT command accepts one parameter: the session ID of the client which
1844 should be terminated, or 0 for all clients. When successful, the REQT command
1847 It should be noted that REQT simply transmits an express message to the
1848 specified client(s) with the EM_GO_AWAY flag set. Older clients do not honor
1849 this flag, and it is certainly possible for users to re-program their client
1850 software to ignore it. Therefore the effects of the REQT command should be
1851 considered advisory only. The recommended implementation practice is to first
1852 issue a REQT command, then wait a little while (from 30 seconds up to a few
1853 minutes) for well-behaved clients to voluntarily terminate, and then issue a
1854 TERM command to forcibly disconnect the client (or perhaps a DOWN command, if
1855 you are logging off users for the purpose of shutting down the server).
1858 SEEN (set or clear the SEEN flag for a message)
1860 Beginning with version 5.80, Citadel supports the concept of setting or
1861 clearing the "seen" flag for each individual message, instead of only allowing
1862 a "last seen" pointer. In fact, the old semantics are implemented in terms
1863 of the new semantics. This command requires two arguments: the number of the
1864 message to be set, and a 1 or 0 to set or clear the "seen" bit.
1866 This command returns OK, unless the user is not logged in or a usage error
1867 occurred, in which case it returns ERROR. Please note that no checking is
1868 done on the supplied data; if the requested message does not exist, the SEEN
1869 command simply returns OK without doing anything.
1872 GTSN (GeT the list of SeeN messages)
1874 This command retrieves the list of "seen" (as opposed to unread) messages for
1875 the current room. It returns OK followed by an IMAP-format message list.
1878 SMTP (utility commands for the SMTP gateway)
1880 This command, accessible only by Aides, supports several utility operations
1881 which examine or manipulate Citadel's SMTP support. The first command argument
1882 is a subcommand telling the server what to do. The following subcommands are
1885 SMTP mx|hostname (display all MX hosts for 'hostname')
1886 SMTP runqueue (attempt immediate delivery of all messages
1887 in the outbound SMTP queue, ignoring any
1888 retry times stored there)
1891 STLS (Start Transport Layer Security)
1893 This command starts TLS on the current connection. The current
1894 implementation uses OpenSSL on both the client and server end. For future
1895 compatibility all clients must support at least TLSv1, and servers are
1896 guaranteed to support TLSv1. During TLS negotiation (see below) the server
1897 and client may agree to use a different protocol.
1899 The server returns ERROR if it does not support SSL or SSL initialization
1900 failed on the server; otherwise it returns OK. Once the server returns OK and
1901 the client has read the response, the server and client immediately negotiate
1902 TLS (in OpenSSL, using SSL_connect() on the client and SSL_accept() on the
1903 server). If negotiation fails, the server and client should attempt to resume
1904 the session unencrypted. If either end is unable to resume the session, the
1905 connection should be closed.
1907 This command may be run at any time.
1910 GTLS (Get Transport Layer Security Status)
1912 This command returns information about the current connection. The server
1913 returns OK plus several parameters if the connection is encrypted, and ERROR
1914 if the connection is not encrypted. It is primarily used for debugging. The
1915 command may be run at any time.
1917 0 - Protocol name, e.g. "SSLv3"
1918 1 - Cipher suite name, e.g. "ADH-RC4-MD5"
1919 2 - Cipher strength bits, e.g. 128
1920 3 - Cipher strength bits actually in use, e.g. 128
1923 IGAB (Initialize Global Address Book)
1925 This command creates, or re-creates, a database of Internet e-mail addresses
1926 using the vCard information in the Global Address Book room. This procedure
1927 is normally run internally when the server determines it necessary, but is
1928 also provided as a server command to be used as a troubleshooting/maintenenance
1929 tool. Only a system Aide can run the command. It returns OK on success or
1933 QDIR (Query global DIRectory)
1935 Look up an internet address in the global directory. Any logged-in user may
1936 call QDIR with one parameter, the Internet e-mail address to look up. QDIR
1937 returns OK followed by a Citadel address if there is a match, otherwise it
1938 returns ERROR+NOT_LOGGED_IN.
1941 VIEW (set the VIEW for a room)
1943 Set the preferred view for the current user in the current room. Please see
1944 views.txt for more information on views. The sole parameter for this command
1945 is the type of view requested. VIEW returns OK on success or ERROR on failure.
1948 QNOP (Quiet No OPeration)
1950 This command does nothing, similar to the NOOP command. However, unlike the
1951 NOOP command, it returns *absolutely no response* at all. The client has no
1952 way of knowing that the command executed. It is intended for sending
1953 "keepalives" in situations where a full NOOP would cause the client protocol
1956 Naturally, sending this command to a server that doesn't support it is an
1957 easy way to mess things up. Therefore, client software should first check
1958 the output of an INFO command to ensure that the server supports quiet noops.
1962 MRTG (Multi Router Traffic Grapher)
1964 Multi Router Traffic Grapher (please see http://www.mrtg.org for more info) is
1965 a tool which creates pretty graphs of network activity, usually collected from
1966 routers using SNMP. However, its ability to call external scripts has spawned
1967 a small community of people using it to graph anything which can be graphed.
1968 The MRTG command can output Citadel server activity in the format MRTG expects.
1970 This format is as follows:
1975 Line 3: uptime of system
1976 Line 4: name of system
1979 MRTG accepts two different keywords. "MRTG users" will return two variables,
1980 the number of connected users and the number of active users. "MRTG messages"
1981 will return one variable (and a zero in the second field), showing the current
1982 highest message number on the system. Any other keyword, or a missing keyword,
1983 will cause the MRTG command to return an ERROR code.
1985 Please get in touch with the Citadel developers if you wish to experiment with
1990 ASYN (ASYNchronous message support)
1992 Negotiate the use of asynchronous, or unsolicited, protocol messages. The
1993 only parameter specified should be 1 or 0 to indicate that the client can or
1994 cannot handle this type of messages. The server will reply OK followed by a
1995 1 or 0 to tell the client which mode it is now operating in.
1997 If the command is not available on the server (i.e. it returns ERROR), or
1998 if the command has not been executed by the client, it should be assumed that
1999 this mode of operation is NOT in effect.
2001 The client may also send any value other than 0 or 1 to simply cause the
2002 server to output its current state without changing it.
2004 When asynchronous protocol mode is in effect, the client MUST handle any
2005 asynchronous messages as they arrive, before doing anything else.
2010 ASYNCHRONOUS MESSAGES
2011 ---------------------
2013 When the client protocol is operating in asynchronous mode (please refer to
2014 the writeup of the ASYN command above), the following messages may arrive at
2018 901 (express message arriving)
2020 There is an express message intended for this client. When the client
2021 receives this message, it MUST act as if it just sent a GEXP command (the data
2022 following the 901 message WILL be a LISTING_FOLLOWS data transfer; in fact,
2023 the current implementation simply executes a GEXP command internally).